1. Field of the Invention
This invention relates to the field of high speed dental handpieces, and in particular to the field of dental handpieces which utilize an optical system for transmitting light to a bur driven by the handpiece.
2. Description of the Prior Art
In present day dental technology it is generally a practice to utilize overhead lights to illuminate a patient's mouth. Overhead illumination is not entirely satisfactory since it is a compromise between sufficient light for the dentist to work by, but not strong enough to be uncomfortable to the patient. Furthermore, overhead illumination must be aimed to strike the oral cavity, and tends to create shadows and bright spots making restorative procedures tedious and visually fatiguing.
An improved method of illuminating the oral cavity utilizes a dental handpiece which carries its own illumination. Known prior art which teaches this modern technique of dental handpiece illumination are: U.S. Pat. Nos. 3,397,457; 3,638,013; 3,758,951; 3,893,242; and 3,897,134.
U.S. Pat. No. 3,397,457 shows how a regular dental handpiece may be modified for carrying illumination to the patient's mouth by means of a fiber optic light system. Illumination is brought to the handpiece from a light source through a separate fiber optic cable which enters the coupling, runs through the handpiece, emerges on the underside of the neck, and ends immediately adjacent the housing. A recognized shortcoming of this arrangement is that shadows may be generated from the single point of light. The fiber optics below the neck bulk the handpiece at this critical point which limits access, increases work effort, and decreases patient comfort. The separate fiber optic cable running along side the supply hose is also awkward.
In U.S. Pat. No. 3,758,951 a fiber optic illumination system is provided which modifies a regular dental handpiece to carry light to the oral cavity. This is accomplished by routing a fiber optic cable from a light source to the handpiece through a center opening in a special shaped supply hose. At the handpiece the fiber optics are completely independent and external of the coupling and the handle and are taped onto the handpiece. Shortcomings of this arrangement include the increased bulk of the external fiber optics at the handpiece, the lack of easy separation of the fiber optics when the coupling is opened, and the bulky supply hose. In addition, immediately adjacent the coupling the fiber optic cable must emerge from the center of the supply hose to run alongside the handpiece. The entire arrangement is awkward and unappealing in appearance.
Although this patent illustrates a four-conduit supply hose to provide the services of turbine air, water, and chip-air and light a total of five conduits would be needed if turbine exhaust were included. A five conduit supply system unduly complicates the handpiece coupling, adds additional bulk to the supply hose, and makes fabrication of the fiber optic cable difficult and expensive, all of which are undesirable.
In U.S. Pat. No. 3,893,242 a fiber optic dental handpiece is disclosed with a most serious shortcoming. In the handpiece the fiber optic channel is substituted for a chip-air tube, making separate chip-air control impossible. An alternate sample of chip-air is provided by tapping off the turbine air tubes in the handpiece. Another shortcoming of this design is that an elastomeric material is used in the handpiece to provide the spring force needed to press the faces of the fiber optics in the coupling firmly together. Elastomeric and plastic elements in the handpiece are adversely affected by autoclaving. In time the elastomer will lose its resiliance and no longer function as an adequate spring. In addition, the optic fibers in the handpiece are constantly flexing. In this design the supply fiber optic cable is cemented into the coupling terminal. This creates a potential problem for replacement of the fiber optic cable since it must have a complete terminal at its distal end.
U.S. Pat. No. 3,897,134 shows a version of a fiber optic dental handpiece which has the fiber optic spring force within the handpiece handle. This shares the problem of U.S. Pat. No. 3,893,242 of being more sensitive to autoclaving, and requiring the fibers in the handpiece to flex.